From e6c4dcb308160115287afd87afb63b5684d75a5b Mon Sep 17 00:00:00 2001 From: "Naveen N. Rao" Date: Mon, 30 Oct 2017 20:42:09 +0530 Subject: [PATCH] powerpc/kprobes: Dereference function pointers only if the address does not belong to kernel text This makes the changes introduced in commit 83e840c770f2c5 ("powerpc64/elfv1: Only dereference function descriptor for non-text symbols") to be specific to the kprobe subsystem. We previously changed ppc_function_entry() to always check the provided address to confirm if it needed to be dereferenced. This is actually only an issue for kprobe blacklisted asm labels (through use of _ASM_NOKPROBE_SYMBOL) and can cause other issues with ftrace. Also, the additional checks are not really necessary for our other uses. As such, move this check to the kprobes subsystem. Fixes: 83e840c770f2 ("powerpc64/elfv1: Only dereference function descriptor for non-text symbols") Cc: stable@vger.kernel.org # v4.13+ Signed-off-by: Naveen N. Rao Signed-off-by: Michael Ellerman --- arch/powerpc/kernel/kprobes.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/arch/powerpc/kernel/kprobes.c b/arch/powerpc/kernel/kprobes.c index 367494dc67d9..bebc3007a793 100644 --- a/arch/powerpc/kernel/kprobes.c +++ b/arch/powerpc/kernel/kprobes.c @@ -600,7 +600,12 @@ NOKPROBE_SYMBOL(kprobe_fault_handler); unsigned long arch_deref_entry_point(void *entry) { - return ppc_global_function_entry(entry); +#ifdef PPC64_ELF_ABI_v1 + if (!kernel_text_address((unsigned long)entry)) + return ppc_global_function_entry(entry); + else +#endif + return (unsigned long)entry; } NOKPROBE_SYMBOL(arch_deref_entry_point); -- 2.20.1